The invention relates to a casing, in particular a plastic casing of a hand-held electronic apparatus, according to the preamble of claim 1.
With the explosive expansion of small electronic apparatuses (xe2x80x9chand-held devicesxe2x80x9d), plastic casings of this type have become a specific mass-produced product. In view of the fact that they house high-quality, expensive and relatively sensitive electronic components and functional groups, they have to satisfy high requirements demanded of the quality and nevertheless have to be produced and equipped simply and cost-effectively. As a rule, it is also necessary to be able to open and securely reclose casings of this type for maintenance and repair purposes. Particular requirements are imposed on the dust seal, the electromagnetic shielding effect and the shock resistance of these casings.
Many of the casings under discussion, also including the plastic casings for mobile telephones, comprise essentially two casino shells made of impact-resistant plastic (for example, ABS plastic), which are connected to each other essentially nonreleasably by means of latching elements or a snap connection or releasably by screw connections. There are also casings in which snap connections and latching connections are combined.
The design, in a manner appropriate for the material involved, of a screw-down dome in a casing of this type always constitutes a compromise between the requirements of plastics technology, on the one hand, and the resultant space required in the apparatus. Since screw-down domes of this type are always formed with a certain clearance with respect to the casing outer wall, due to requirements to do with plastics technology, their presence as a whole results in xe2x80x9csurface consumptionxe2x80x9d, which always exceeds their actual cross-sectional area. With increasing miniaturization of a very wide variety of hand-held devices, for example mobile telephones, organizers, pocket translators, hand-held PCs cordless telephones, this problem is becoming ever more relevant.
The invention is therefore based on the object of specifying a casing of the generic type which can be opened and reclosed without particular complexity, and in which the ratio of interior space which can be used to the overall volume is very good.
The invention includes the essential concept of providing, on the casing parts to be connected, holding and hook elements and a separate locking element which to a certain extent wedges the holding elements to the inner wall of the respective outer casing part. By means of a hook-like design of at least some of the holding elements, it is ensured that a closing force which can be applied easily is opposed by a very high opening force if the locking element is in undisturbed engagement with the holding elements. If, in contrast, said locking element is removed from the casing or is deformed in a suitable manner, it loses its locking or wedging effect, and the housing can again be opened easily.
In a preferred design, the locking element is fitted into a guide in a first casing shell or into holding elements provided behind said casing shell and is engaged around by holding elements, which act in a hook-like manner, on a second casing shell, or, if the locking element is appropriately shaped, said holding elements engage therein. As a result of this engagement around or in said locking element, the hook elements of the second casing shell are pressed against corresponding contact surfaces of the first casing shell. If said contact surfaces are designed with suitable frictional surfaces or else undercuts or the like, a force- and/or form-fitting connection is produced as a result, which connection has a high holding force so long as the locking element is in situ and is in its form which produces the locking effect.
The effect under discussion is produced in an expedient manner in the region of the casing side surface, i.e. the longitudinal edge sections of the casing shells, in which case, with regard to compensation of any manufacturing tolerances and a desirable, certain elasticity of the connecting means, the provision of a plurality of hook elements spaced apart from one another along the edge is expedient.
In one design, in which holding elements and hook elements are provided on both casing shells for engagement with the locking element, an alternating sequence of elements formed on the first and second casing shells in the edge longitudinal profile is expedient, in order to achieve a uniform contact-pressure effect over this profile.
In a particularly simple design, a flat metal plate can be used as the locking element, which plate has at least one edge which is matched to the edge profile of the casing shells, and is engaged around by the holding elements and hook elements of the casing shells. Also advantageous is a design in which this metal plate extends essentially over the entire width of the casing, with the result that two opposite edges serve for locking together the holding elements of the first and second casing shells, which holding elements are adjacent to said edges and lie opposite one another.
If the metal plate is flexurally elastic, compression or tension directed essentially vertically onto its surface can result in a flexural deformation, as a result of which the locking effect is cancelled and the casing shells can be separated from each other again.
An action of this type on the metal plate is possible by means of at least one suitably positioned actuating opening in one of the casing shells. Said opening may also be closed with a closure element which, in order to open the casing, is either removed or is designed displaceably or flexibly to such an extent that it itself can be pressed to a certain extent onto the metal plate as an extended compression pin.
In an alternative design, provision may also be made for the casing to be formed in such a manner that the metal plate is displaced within the casing from a first position, in which there is engagement with the holding elements and hook elements, into a second position in which this engaged state is cancelled. This can be achieved in a simple manner by its edge(s) having, for example, a meandering or serrated profile rather than a rectilinear profile.
In another design, the locking element is of wire- or pin-shaped design and is fitted into a corresponding guide on the one casing part in such a manner that when the other casing part is fitted, its holding elements slide perpendicularly with respect to the longitudinal profile of the wire or pin, past said profile and become hooked with projecting sections behind it, in which case they are simultaneously pressed against the inner wall of the casing part bearing the wire- or pin-shaped locking element.
Also in this designxe2x80x94with an appropriately flexurally elastic design of the locking elementxe2x80x94release of the locking and therefore of the connection of the casing parts is possible by a flexural deformation. Furthermore, in this case too the locking element can be shaped in such a manner and mounted displaceably such that the transition from an engaged position into a disengaged position with regard to the holding elements or hook elements is implemented by a displacement of the locking element. Both the deformation and the displacement can be carried out in a casing part via actuating sections which are provided for this purpose.
However, a wire- or pin-shaped locking element can also be designed relatively easily such that it can be pulled out of the closed casing, whereupon the holding elements relax and the connection between the casing parts is canceled.
In a special design, the wire-shaped locking element is in the form of a clasp or clip which extends over mutually opposite sections of two casing longitudinal edges and the casing end side connecting said longitudinal edges and thereforexe2x80x94in a similar manner as the abovementioned metal platexe2x80x94causes locking in a plurality of edge regions simultaneously. Also, with an appropriate design of the casing, a clip or clasp of this type can be pulled out of said casing in order to release the connection of the casing parts.